March 19, 2013

Abnormalities in Pleistocene Homo

An excess of congenital defects is certainly compatible with high levels of inbreeding, and the publication of the Denisova genome clearly suggested "extremely low" genetic diversity in that Pleistocene human. It'll be interesting to see if more ancient DNA data will reveal high levels of inbreeding consistent with the abundance of genetic abnormalities evident in the anthropological record.PLoS ONE 8(3): e59587. doi:10.1371/journal.pone.0059587

An Enlarged Parietal Foramen in the Late Archaic Xujiayao 11 Neurocranium from Northern China, and Rare Anomalies among Pleistocene Homo

Xiu-Jie Wu et al.

We report here a neurocranial abnormality previously undescribed in Pleistocene human fossils, an enlarged parietal foramen (EPF) in the early Late Pleistocene Xujiayao 11 parietal bones from the Xujiayao (Houjiayao) site, northern China. Xujiayao 11 is a pair of partial posteromedial parietal bones from an adult. It exhibits thick cranial vault bones, arachnoid granulations, a deviated posterior sagittal suture, and a unilateral (right) parietal lacuna with a posteriorly-directed and enlarged endocranial vascular sulcus. Differential diagnosis indicates that the perforation is a congenital defect, an enlarged parietal foramen, commonly associated with cerebral venous and cranial vault anomalies. It was not lethal given the individual’s age-at-death, but it may have been associated with secondary neurological deficiencies. The fossil constitutes the oldest evidence in human evolution of this very rare condition (a single enlarged parietal foramen). In combination with developmental and degenerative abnormalities in other Pleistocene human remains, it suggests demographic and survival patterns among Pleistocene Homo that led to an elevated frequency of conditions unknown or rare among recent humans.

13 comments:

"An excess of congenital defects is certainly compatible with high levels of inbreeding"

I have long suspected that the success of modern humans is a product of hybrid vigour resulting from the wide expansion of a succession of populations rather than a simple expansion of a single 'advanced' population. This paper tends to reinforce such speculation. The 'modern' gene pattern is from a widespread population, probably from SW Asia, not a product of a single small population.

That's cool and very relevant. Amerindians show the lowest intragroup diversity levels among modern human populations and some of the more archaic marital alliance systems driving high levels of inbreeding. This supports the idea inherent in the out-of-America theory that they are Mid-Pleistocene relics and not a recent offshoot from the Old World.

> I have long suspected that the success of modern humans is a product of hybrid vigour resulting from the wide expansion of a succession of populations rather than a simple expansion of a single 'advanced' population. <

And yet the most advanced human races seem to generally have the least genetic diversity and the least advanced human races have the most.

It would be interesting to see to what extent genetic diversity correlates with IQ and GDP.

Of course it depends what you mean by "success". Insect species are far more numerous and mammals appear to have been on the decline for tens (hundreds?) of thousands of years.

I suppose that we would have to distinguish mere survival from the more human values like high culture.

Sorry to be breaking a rule here about staying on topic, however I do not know how to start a new thread. I took the skull subrace test and came up as Dinarid on two and Irano Nordic on the last one. How can I post pics to get an "expert" opinion? Is the cranio shape stuff still considered scientific? Thanks

"And yet the most advanced human races seem to generally have the least genetic diversity and the least advanced human races have the most".

Do you think so? I suppose it would depend on what you mean by 'advanced'. The usual interpretation would place humans at the geographic margins as being the most 'primitive', such as Australian Aborigines, Khoisan, South American Indians etc. Presumably groups at the margins would be more inbred than those in the centre of things.

"Of course it depends what you mean by 'success'".

Quite. Success for humans is often cultural, which also appears to undergo 'hybrid vigour' at times. For example I would be quite sure that the Austronesian expansion was the result of the blending of East and Southeast Asian technologies and the Indo-European expansion (whatever that term represents) was the product of the mixing of Anatolian and steppe cultures. I'm sure we could find other examples.

"mammals appear to have been on the decline for tens (hundreds?) of thousands of years".

Thousands of years rather than tens of thousands. Mammals in various regions were generally doing alright until humans arrived. And although their extinction is associated with reduced habitat rather than over-hunting this reduced, or broken, habitat has the effect of reducicing hybrid vigour.

I also did the anthro face measurement. My best match was Greek. 100% on the 14 and 11 measurements. Which is strange as most of my family came from the British Isles supposedly. However some emigrated there from other parts of Europe. I have several links to Arpads descendants in a few lines. I supposedly have Jewish and Native American ancestry as well. Should I just do the 23 and me test? Which test works best with this Dodecad? I would love to find my origins as its too complex to figure out. Is there anyone that can help me post my photos? Thanks

tt, it has been argued that genetic diversity is optimum in Eurasia, too great in Africa and too small with Amerindians and on the "margins". Moreover, if you mix a high IQ population with a low IQ population, yet get an IQ somwhere near the middle. eg. the Afro-American IQ (85) is intermediate between the African (70) and European IQ (100). Its not a simple matter of "more is better". It seems hasty if not ideological to assume that hybridisaton played a key role in the success of early humans. There may have been genetic adaptations that played a vital role. I dont see that you can solve that question merely because of some inbred skeletons. Obviously gene flow is an important part of evolution but it is not the only part, bottle necks also play a role.

@apostateimpressions: "Moreover, if you mix a high IQ population with a low IQ population, yet get an IQ somwhere near the middle. eg. the Afro-American IQ (85) is intermediate between the African (70) and European IQ (100)."

Va, have a look at this documentary which showed recently on Norwegian tv, _Race: Science's Last Taboo_. It builds a picture of how science would pull society in the direction of limited immigration and selective breeding and how leftist "moral" sentiment would pull society in the opposite direction regardless of the future consequences.

http://www.youtube.com/watch?feature=player_embedded&v=tR2iGZlLLUo

I dont think that anyone doubts the racial difference in IQ. Hundreds of large scale IQ studies have been conducted since the early 20th century in America. The difference in racial IQs has remained constant. What has been disputed is the _cause_ of the difference in racial IQ. Leftists adopted the 'nurturist' explanation and they predicted that they could equalise or significantly lessen the difference in racial IQ through political, cultural and educatinal methods. After decades of 'positive' discrimination in schools and massive government funding, positive image campaigns, attempts to remove cultural bias from IQ tests etc., the IQ difference between whites and blacks in the US has remained the same. In fact there is evidence that modern urban dysgenics is doing more harm to the black IQ in the US than to whites.

I will get back to you with some of the academic literature on the subject.

There's a study on this very blog that links IQ to sperm fertility. Which means IQ is linked to "fitness" which means it indeed means something. It's sad that science has become so politicized you can't state obvious facts. What's next? Mention people with red hair have higher IQs that blondes and you are racist against blondes? Another fact, but I'm sure mankind's purpose on earth isn't to make nifty television manufacturing technology.

But back to the topic I have to wonder if the reason some defects and injuries are found in caves is due to leaving the infirm by the campfires to do work like processing skins.

The "crebs" skeleton in qualfez (sp?) comes to mind. Also, there's an inordinate amount of assymetry on most male neanderthal skeletons. Meaning they did something with one hand, which is thought to be holding skin in teeth and scraping the skin to remove excess flesh, with one hand.

I doubt most of the remains are intentional burials because you don't bury someone 20 feet away from where you sleep. So we probably only get these finds when there's some catastrophe, which is usually the case in more modern sites.

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